I've been a member of The Matrix now for about a year, and I like it. In the past, I was a member of the Rock for several years, so I have a point of comparison. The Matrix is cheaper. It is more no frills The Rock, and I like that. They've been doing some renovations and equipment upgrades in the past year, and they've got plenty of machines in good condition. The weight room is pretty well stocked. They've got a variety of classes, although I have never taken any, and they offer all sorts of trainer options - private, semi-private, and small group, the latter of which I've done and I think it's a good value. They have a certified sports massage therapist on staff, I believe.
If you go to their website, you can print out a 14 day pass to try it before joining.